1. Field of the Invention
The present invention relates to an article and a method to provide improved fuel tank components in a motor-vehicle, and in particular, a welded baffle component to be used in motor vehicle fuel tanks.
2. Description of the Prior Art
Baffles have been used for many years in fuel tanks to reduce the effect of the fuel sloshing when the vehicle is in motion. When a vehicle is moving, fuel can flow rapidly from one side of the tank to the other. In a fuel tank without a baffle, the fuel sloshing within a tank can cause instability in the vehicle and reduce control and potentially cause it to swerve or tip over. Additionally, the sloshing of a large amount of fuel against the walls of the tank can cause severe structural strains on the tank walls. A correctly placed baffle interrupts the sloshing fuel and slows the fuel wave so the effect of the fuel movement is less, thereby increasing the stability of the vehicle and reducing the strain on the walls of the tank.
Baffles in fuel tanks are becoming more important as larger automobiles are being produced by the automakers. Large-sized sports utility vehicles are now common on the road. Automakers have many even larger sports-utility vehicles planned for release in the next few years. These large vehicles have poor fuel efficiency compared to smaller vehicles and require larger fuel tanks. They also have a higher center of gravity than typical passenger vehicles, which makes them inherently less stable than passenger vehicles. With large volumes of fuel slosh, vehicle stability and control can become an issue. Using effective baffles in these vehicles reduces concerns.
There are two critical aspects of baffle design: the attachment method of the baffle to the fuel tank and the shape of the baffle. Baffle design must also be balanced with weight, cost and ease of manufacture considerations. Because of the weight issue, the majority of fuel tanks used on passenger vehicles are plastic, so the attachment method must be consistent with plastics manufacturing. Plastic fuel tanks are, however, not as strong as metal and require the baffle to also act as a support mechanism for the tank.
According to NASA studies for rocket fuel tanks, the ideal baffle design is made up of rigid annular rings. These rings, however, add a significant amount of weight to a vehicle and make the tank unduly heavy. This is not acceptable in automobile design where weight is such a significant factor.
U.S. Pat. No. 6,220,287 B1 issued to Wolf uses a plurality of semi-round baffles in different locations extending from the inner side walls of the tank towards the center. While lighter than the annular ring design, the manufacturing of a tank containing these baffles would encompass multiple process steps to attach the many baffles and would be cost-prohibitive in the auto industry.
In U.S. Pat. No. 5,850,933 issued to Pazik, a plastic molded fuel tank is described which contains a traverse baffle that is molded into the tank. While the manufacturing is simplified in this design, the baffle design is non-ideal because the baffle only supports the plastic tank in one direction.
In U.S. Pat. No. 4,526,286 issued to Jung et al., a thermoplastic fuel tank is also described where the baffles are molded into the tank. The baffles are protrusions from the tank walls with openings in the baffles. This is a better baffle design for dampening and strength because of the openings and two-direction strengthening. However, the baffle protrusions and openings in the baffles make for a very complicated molding tool with many slides and steps. The cycle time in the tool is thus increased, making it less feasible for the high volume automotive industry.
Many of the above concerns are dealt with in U.S. Pat. No. 4,350,258 issued to Rogers. The fuel tank baffle is mounted in an interlocking arrangement to the fuel tank. In this patent, a simple baffle is added to the fuel tank without complicating the manufacturing, but the added component creates a rattle risk. An interlocking arrangement can loosen over time and cause the noise that a vehicle driver or passenger may complain about.
Welding of the baffle to the fuel tank was described in U.S. Pat. No. 1,562,074 issued to Baum. The weld could not be made inside the metal tank. The baffle protruded through the tank and was welded from the outside. This method of welding from the outside created a weak point at the joint, which is undesirable.
From the above it is seen that there remains a need for a system and method of manufacturing a baffle inside a vehicle fuel tank that is cost effective for mass production, prevents sloshing fuel from causing vehicle instability, minimizes weak points, aids in the structural integrity of the fuel tank and fits securely to prevent noise.
In accordance with the present invention, a fuel tank baffle is provided where a vee-shaped baffle is plastic welded to the interior of the plastic fuel tank. The baffle is welded to the fuel tank while the fuel tank is still hot from thermoforming.
A fuel tank, made up of a thermoplastic material, is generally manufactured using a thermoforming process. When the tank is cooled enough to retain its shape, but still hot from the thermoforming process, the plastic baffle is placed inside the warm fuel tank. The baffle is then plastic welded to the fuel tank at the top of the baffle.
The baffle is a vee with a rounded vertex at its bottom, the bottom portion hereinafter referred to as the vertex. The vee-shape allows the baffle to support the fuel tank while the fuel tank cools and gives the fuel tank added structural support when in use in a vehicle.
In the preferred embodiment of the invention, a series of holes perforate the baffle to keep the fuel flowing from the front of the vehicle to the back of the vehicle or back to front or side to side at a minimum velocity. Braces are added to the sides of the baffle to increase the rigidity of the baffle. The top of the vee have two sets of stepped xe2x80x9cfeetxe2x80x9d sticking outward therefrom. The ends of the feet serve two purposes. One set of feet sink into the warm fuel tank to gain better retention of the baffle by the fuel tank. The second set of feet creates a positive stop point for the insertion of the baffle to the fuel tank to aid the assembly.
Advantages of the present invention include the manufacturing of the baffle apart from the manufacture of the fuel tank. The shape of the baffle is not limited by the shape of the fuel tank, as in previous designs, since it is manufactured separately. The unrestricted unique shape of the baffle also reduces the noise of the fuel sloshing back and forth in the tank. The fuel tank can be produced cheaply and efficiently by not having to consider the geometry of the baffle in the tool design. The baffle can be molded separately, allowing for an ideal shape for a fuel tank baffle, without complicated molding. The finished product is lightweight and has high structural integrity for a plastic component.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.